What exactly doe a cold air induction or cold air intake do to improve gas milage?
A cold air induction does not improve gas mileage, rather it increases performance. Cold air is denser than warm air, it has more molecules per volume than warm air, this means that more fuel or gas can be carried in on the charge ( the fuel attaches itself to the air molecules). Unfortunately this only works well when the induction velocity is high where the air/fuel mix is kept highly agitated. At lower intake velocities the air needs to be warmed, either by Water heating the manifold, or by heating the induction air with heat from the exhaust manifolds. variations between the two extremes are controlled by a flap valve which mixes heated and cooled air to provide the correct temperature for ignition of around 80 deg C. Its this accurate control of intake temperature that improves gas mileage.
